Miklós László

Lignan production by Ipomoea cairica callus cultures

Abstract Callus cultures were established from the plant Ipomoea cairica (L.) Sweet, to verify whether they produce the same lignans, arctigenin and trachelogenin, as the intact plant. Medium components (auxin, pH, carbohydrates) were changed to influence the production level of the two compounds. Optimal conditions for culture growth and lignan production were determined, and the implications for in vitro lignan production are discussed.

Monitoring of haploid maize cell suspension culture conditions in bioreactors

Maize (Zea mays L.) haploid cells were cultivated in a 1500 ml aerated and stirred batch bioreactor using modified BM medium. Cell growth was highly affected by pH and dissolved oxygen, and we observed two fairly distinct growth phases. During the first two days after inoculation at pH 5.8, oxygen consumption was high and the cells lowered the pH to a value around 4.3. After this period the pH stabilized at 4.5 and the dissolved oxygen reached a steady level. Decreasing dissolved oxygen concentration leads to lower growth rate and to higher pH. Both events mean stress conditions for the cell culture and probably result in increased genetic variability, and the loss of regeneration capacity. The stress condition during the adaptation phase can be eliminated by decreasing the pH of the medium to 4.7 before inoculation and by keeping dissolved oxygen above 40%. These conditions provide prolonged exponential growth dynamics and the cell suspensions could be the basis of large scale cultures also.

Lignan production by Ipomoea callus from carbohydrates

Lignans have proved to be interesting compounds for their possible antitumour, antiHIV and Ca2+ antagonist activity. The tropical climbing shrub Ipomoea cairica (L.) Sweet contains two particularly promising lignans, arctigenin and trachelogenin. Callus cultures were established from the plant to examine whether the lignan production is conserved in vitro. To modify the lignan production, carbohydrates in the medium were changed. Different sugars and sucrose levels were examined. Lignans were synthesized by the cultures, the sugar level and quality had a major influence on lignan production.